Does anyone know how to fix this weird Faces in Blender?
Enter edit mode (Vertex) press 1 on top of your keyboard to filter by vertices. You´ll notice you have double vertices on the corners. Since they're together, select the corner with weird normals and hit ALT+M (merge at the middle). This will join those vertices and correct the normals. 

Else, you have more vertices on the faces that you need to delete. Select a vertex, press "X and D" in that sequence.
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BFCT_Schiller